; Return with 2 HEX digits in [A] from keyboard
; If abort, Carry flag set & ESC is returned in [A]
; All registers unchanged except [A]    (ZILOG)
 
GETHEX:
	PUSH	BC
	LD	C,RDCON			 
	CALL	BDOS		;Get a character from keyboard & ECHO
	CALLUPPER
      CP	A,ESC
	JR	Z,HEXABORT
	CP	'/'		;check 0-9, A-F
	JR	C,HEXABORT
	CP	'F'+1
	JR	NC,HEXABORT
	CALL	ASBIN		;Convert to binary
	SLA	A
	SLA	A
	SLA	A
	SLA	A		;Shift to high nibble	 
	LD	B,A		;Store it
	PUSH	BC		;Because CP/M destroys BC
	LD	C,RDCON			 
	CALL	BDOS		;Get a character from keyboard & ECHO
	POP	BC
      CALL  UPPER
	CP	A,ESC
	JR	Z,HEXABORT
	CP	'/'		;check 0-9, A-F
	JR	C,HEXABORT
	CP	'F'+1
	JR	NC,HEXABORT
	CALL	ASBIN		;Convert to binary
	OR	A,B		;add in the first digit
	OR	A,A		;To return NC
	POP	BC
	RET
;
HEXABORT:
	SCF			;Set Carry flag 
	LD	A,ESC
	POP	BC
	RET
;
ASBIN:SUB	30H		; ASCII TO BINARY CONVERSION ROUTINE
	CP	0AH 
	RET	M
	SUB	07H 
	RET
;
UPPER:CP    A,'a'
      RET   C
      CP    A,'z'+1
      RET   NC
      SUB   A,'a'-'A'
      RET